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Full text of "Alexander von Humboldt"

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dense smoke. A broad, but brightly luminous arch
of light, first white, then yellow, "bounds the dark
segment. Bnt as this luminous arch rises subse-
quently to the smoky-grey portion of the horizon, it
is not merely a contrast with the brighter portion.
In the extreme north, very near the magnetic pole,
the smoky portion of the sky is less dark, and some-
times does not appear at all
"The unsteady and scintillating luminous arch, some-
times stands for hours in the horizon, before any rays
or groups of sparks separate from it, and rise to the
zenith. The more violent the discharges of the aurora
borealis are, the more actively do the colours play
from violet and bluish-white, through all the shades,
to green and purple. Magnetic columns of fire rise
from the luminous arch, sometimes alone, and min-
gled with black rays, like dense smoke; sometimes
simultaneously from opposite points of the horizon,
uniting in a scintillating sea of fire, whose splendour
no description can portray, as its waves of light
change and vary in form and colour every moment.
This motion increases the brilliancy of the pheno-
menon. The rays at last unite in that point of the
firmament, answering to the direction of the magnetic
needle, and form what is called the crown of the
aurora borealis. But this crown is rarely perfect,
and always immediately precedes the termination of
the northern light. The rays .then grow shorter, rarer5
and more colourless, the crown and the arches of light
fade, and soon after, the sky is only covered by irre-
gularly grouped, broad, pale, almost ash-grey, im-
movable spots. They also vanish, before the trace of
the dark srnoke-like circle standing deep in the
horizon is lost. At last nothing remains of the whole
scene but a white thin cloud, feathered at the edge,
or separated into small round divisions/*